Is There A Need For Stochastic Inputs To Mimic Real-World Biology And Environment?
Quite an interesting question, this sort of computational representation of biological systems are at the forefront of what we are trying to accomplish algorithmically. 

This can be tackled via a variety of coordinate frames and problem formulations and could be thought of quite philosophically, as it pokes at some deep questions such as free-will and consciousness more generally. 

For example, we could take the assumption that based on everything we know physically, the universe is completely deterministic. In this case, implementing deterministic functions for these variables makes quite a bit of sense and seems like the obvious choice. However, we can easily imagine that for at least some of this dynamic variables a stochastic representation would be both simpler(computationally) as well as giving better approximations to what we see in the real-world.

So it really is a question of how much value you see from implementing a system like this, and which representation you think would be most effective.